Pretensioned knockdown concrete wall form panel



Dec. 30, 1969 v, S 7 3,486,729

PRETENSIONED KNOCKDOWN CONCRETE WALL FORM PANEL Filed Nov. 6, 1967 3Sheets-Sheet 1 FIG. Ii FIG. 2

INVENTOR. VERNON R SCH/MMEL ATTORNEY v. R. SCHIMMEL 3,486,729

PRETENSIONED KNOCKDOWN CONCRETE WALL FORM PANEL Dec. 30, 1969 3Sheets-Sheet 2 Filed NOV. 6, 1967 FIG. 4

INVENTOR. VERA/0N R. SCH/MMEL A TTOR/VE) Dec. 30,1969 v. R. SCHIMMELPRETENSIONED KNOCKDOWN CONCRETE WALL FORM PANEL 3 Sheets-Sheet 5 FiledNov. 6, 1967 FIG. 10

FIG. 9

' INVENTOR. VERNON R. SCH/MMEL FIG. I2-

ATTORNEY.

United States Patent 3,486,729 PRETENSIONED KNOCKDOWN CONCRETE WALL FORMPANEL Vernon R. Schimmel, Arlington Heights, 11]., assignor to SymonsMfg. Company, Des Plaines, Ill., a corporation of Delaware Filed Nov. 6,1967, Ser. No. 680,796 Int. Cl. E04g 9/08 US. Cl. 249-189 6 ClaimsABSTRACT OF THE DISCLOSURE The present invention relates generally toconcrete wall forms and has particular reference to a prefabricatedrectangular concrete wall form panel which comprises a rectangularplywood facing and a rectangular reinforcing frame in the form of steelstudding, the panel being adapted to be arranged in an upstandingposition and also in edge-to-edge relationship with similarprefabricated panels in order to form with such similar panels one sideof a concrete wall form into which wet concrete may be poured forwall-forming purposes. Concrete wall form panels of the type underconsideration also find use in connection with the formation ofhorizontal floor and ceiling slabs and, in such an instance, they arearranged in edge-to-edge relationship with the panel facings lying in acommon horizontal plane so that the concrete may be poured on thecontinuous unbroken upwardly presented slab-supporting face that isformed by the upper surface of the facings.

Such concrete wall form panels are manufactured in sizes which vary bothas to length and width. In the panels of large size, transverseintermediate reinforcing members or crossbars of steel extend betweenthe marginal longitudinal frame members of the rectangular reinforcingstudding at spaced regions therealong and serve to reinforce the medialregions of the plywood facings against outward bulging under the thrustof the hydrostatic head of the poured concrete. The marginal framemembers, both longitudianl and transverse, are constructed and shaped sothat they will cooperate with various articles of concrete hardware suchas (l) clamping devices (bolt and wedge assemblies) for drawing theedges of adjacent panels together, (2) horizontal tie rods which extendtransversely across the concrete wall form and have the ends thereofextending between adjacent panels and attached or connected to theaforementioned clamping devices, (3) waler clamping devices, and (4)other accessory hardware items. Insofar as the plywood facing of aconcrete wall form panel of the type under consideration is concerned,the longitudinal and transverse steel frame members of the rectangularreinforcing studding are formed with inwardly extending ribs whichdefine a marginal recess around the inside rim of the studding and theedge portions of the plywood facing seat within such marginal recesswith the inside face or surface lying flush with the inner edges of theframe members to the end that the inner face of the panel as a whole3,486,729 Patented Dec. 30, 1969 presents a smooth, continuous, unbrokenplanar surface. These structural features of a conventional or standardconcrete wall form panel have been preserved in the improved panel ofthe present invention.

A panel of the general type briefly outlined above is possessed ofcertain limitations which are obviated by the present invention. Amongthese limitations is the tendency for the various steel crossbars toflex or bend outwards under the tremendous outward pressure of thepoured concrete against the plywood facing. To increase the number ofcrossbars or to employ a heavier gauge steel in the construction of thecrossbars would be to increase the weight of the panel beyond acceptablelimits. According to the present invention, there is provided novelmeans whereby the individual crossbars are pretensioned against flexingwhen lateral thrust is applied thereto and the provision of such meansin connection with a concrete wall form panel constitutes one of theprincipal objects of the present invention.

Another limitation that is attendant upon the construction and use of aconventional steel studded concrete wall form panel resides in thedifficulty which is encountered in a plywood facing replacementoperation. It is the current practice to provide flat diagonal braces atthe corner regions of the permanently welded rectangular reinforcingstudding and to rivet the plywood facing to these braces. This practiceis not altogether satisfactory in that not only is it difficult toremove and replace the rivets when plywood facing substitution isrequired, but also after a period of use, particularly in inclementweather, repeated exposure of the plywood facing to moisture causesshrinkage thereof so that the rivets pull away from the plywood and thenet result is that the rivet heads and their surrounding voids leaveundesirable marks in the hardened concrete wall. This limitation also isobviated by the present invention in that a novel knockdown panelconstruction is provided wherein the longitudinal and transversemarginal .frame members of the rectangular reinforcing studding arecapable of being easily separated to release the panel facing which isheld to the crossbars by a comparatively small number of screws whichextend into the plywood facing from the outside thereof. After thescrews are removed, the panel facing is then released from the studdingand a new plywood facing may be substituted by a reversal of theknockdown operation.

It is a further feature and object of the present invention that thepretensioning means by which the crossbars of the panel are rigidified,as described above, also constitutes the clamping means whereby thelongitudinal and transverse frame members of the steel studding arereleasably held together.

Other objects of the invention and the various advantages andcharacteristics of the herein disclosed concrete wall form panel will bereadily apparent from a consideration of the following detaileddescription.

The invention consists in the several novel features hereinafter setforth and more particularly defined by the claims at the conclusionhereof.

In the accompanying three sheets of drawings forming a part of thisspecification, a concrete wall form panel embodying the invention, thatis, the features briefly set forth above, is illustrated in detail.

In these drawings:

FIG. 1 is a fragmentary perspective view of a portion of a conceretewall form employing a multiplicity of the panels of the presentinvention and showing the same operatively connected together inedge-to-edge and opposed relationship;

FIG. 2 is an enlarged horizontal sectional view taken on the line 2-2 ofFIG. 1;

FIG. 3 is an outside or rear plan view of one of the panels of FIG. 1;

FIG. 4 is an enlarged horizontal sectional view taken on the line 44ofFIG. 3;

FIG. 5 is an enlarged vertical sectional view taken on the line 5-5 ofFIG. 4;

FIG. 6 is an enlarged fragmentary exploded perspective view of a cornerfastening nut and bolt clamping assembly that is employed in connectionwith the invention;

FIG. 7 is a sectional view similar to FIG. 2 but showing one of the twoadjacent panels removed, the other panel being shown in its freeunattached condition;

FIG. 8 is an enlarged fragmentary detail side elevational view of aportion of the panel of FIG. 3, the view being taken in the direction ofthe arrow and limited by the confines of the line 88 of FIG. 3;

FIG. 9 is an enlarged fragmentary end elevational view of a cornerregion of the panel of FIG. 3, the view being taken in the direction ofthe arrows that are associated with the line 99 of FIG. 3;

FIG. 10 is a perspective view of a captured wedge and an associatedT-bolt that are employed in connection with the invention;

FIG. 11 is an enlarged horizontal sectional view taken on the line 11-11of FIG. 3; and

FIG. 12 is a side elevational view of one of the tensioning rods thatare employed in connection With the present invention.

Referring now to the drawings in detail and in particular to FIG. 1, afragmentary portion of a composite concrete wall form is designated inits entirety by the reference numeral 10, the form embodying a number ofthe improved pretensioned knock-down panels 12 of the present invention.The wall form 10 is made up of two spaced apart series 14 and 16 of therectangular Wall form panels 12, with the panels of each series beingarranged in a vertical position and edge-to-edge relationship. Thepanels 12 of the two series are maintained in their parallel spacedapart relationship by means of fiat slotted tie rods 18 in a manner thatwill be made clear presently.

The various panels 12 of the concrete wall form 10 are of theprefabricated, steel-studded type in that they consist of rectangularplywood facings 20, together with marginal studding in the form ofrectangular steel reinforcing frames 22 which extend around and enclosethe plywood facings and consist of vertical and horizontal frame members24 and 26 (see FIG. 3). At appropriate levels in each wall form panel,intermediate horizontal crossbars 28 which are of special constructionand have associated therewith novel pretensioning means extend betweenthe opposed vertical frame members 24 of the rectangular reinforcingstudding and are releasably secured in position therebetween in a mannerthat will be set forth in detail presently. According to the presentinvention, the various crossbars 28 serve a five-fold purpose. Firstly,they serve as a means whereby the medial regions of the vertical framemembers 24 are releasably held in position against the ends of thecrossbars. Secondly, they serve as tensioning members whereby the entirepanel as a whole is rigidly pretensioned. Thirdly, they have associatedtherewith tensioning means which serves to flex the crossbars in adirection which resists the outward thrust that is imparted to thecrossbars at the time the wet concrete is poured against the innersurface of the plywood facing of the panel. Fourthly, they serve asclamping members which serve to draw the two vertical frame membersinwardly toward each other and against the longitudinal edges of theplywood facing so as to capture these edges and assist in maintainingthe plywood facing in position within the confines of the rectangularframe that constitutes the reinforcing studding. Fifthly, the crossbarsserve as anchor members for the medial regions of the plywood facing andeliminate the need for using diagonal braces and rivets such as haveheretofore been considered necessary in the construction of aconventional steel-studded plywood concrete wall form panel.

The vertical frame members 24 and the horizontal frame members 26 are ofsimilar construction insofar as their cross-sectional shape isconcerned. Therefore, a description of one of them will largely suflicefor a description of the others, identical reference numerals beingemployed to assist in the comparison. Each frame member is in the formof an elongated length of rolled steel stock which, as best shown inFIGS. 9 and 11, comprises spaced apart outer and inner coplanar siderail portions 30 and 32, and inwardly extending intermediate throughsection 33. The latter consists of outer and inner trough sides 34 and36 and a slightly inclined trough bottom 38. The inner side rail portion32 and its adjacent inner trough side 36 establishes a right anglerecess 40 within which the adjacent edge portion of the plywood panelfacing 20 seats. The outside edge portion of the outer side rail section30 is provided with an inturned flange 42 which lends rigidity to theframe member as a whole. At the corner regions of the panel, as shown inFIGS. 1 and 9, the horizontal frame members 26 are recessed at theirends in conformity with the cross-sectional shape of the vertical framemembers in order to attain proper interfitting between the longitudinaland transverse frame members at said corner regions of the panel. Thetrough bottom 38 is inclined outwards in the direction of the inturnedflange 42 with the result that the inner trough side 36 is of greaterdepth than the outer trough side 34.

In order to secure the vertical and horizontal frame members 24 and 26together at the corner regions of the panel, the corner fastening orclamping assembly which is illustrated in FIGS. -6 and 9 and isdesignated in its entirety by the reference numeral 50 is employed, itbeing understood that there is an assembly 50 at each corner of thepanel. Said assembly comprises a fastening bolt 52 having a block-likehead portion 54 and a cylindrical shank 56. The latter is adapted toreceive thereover a washer 58, the nut being received on an externallythreaded end portion 62 of the shank 56. Said end portion 62 is turnedlaterally at a small angle to accommodate the angular inclination of thebottom 38 of the intermediate trough section 33 of the adjacent verticalframe member 24 (see FIG. 9). The block-like head portion 54 of theassembly 50 is fixedly connected by a bolt 64 to the bottom 38 of theintermediate trough section 33 of the adjacent horizontal frame member26. The shank 56 of the corner clamping assembly 50 projects through ahole 68 in the bottom 38 of the intermediate trough section 33 of theadjacent vertical frame member 24 so that after application of thewasher 58 and the nut 60 as shown in the drawings, the cornerconnections between adjacent frame members 24 and 26 will be complete.It is to be noted at this point that the four fastening or clampingassemblies 50, in combination with certain additional fastening meansthat are associated with the various crossbars 28- and will be describedsubsequently, constitute substantially the sole means for maintainingthe components of the panel 12 in its assembled relationship.

Referring now to FIGS. 1, 4, 5, 7 and 8 wherein the details of thevarious crossbars 28 are best illustrated, each crossbar, like each ofthe frame members 24 and 26, is of rolled steel stock and is generallyof U-shape in cross section so as to provide a channel consisting ofspaced apart sides 70 and a bottom 72. The crossbars bridge the distancebetween the opposed vertical members 24 of the frame 22 of the panel 12at the selected elevations and the channel sides 70 are provided withoutturned flanges 74 which lie flush against the inside faces of theplywood facing 20 and are secured thereto by rivets 76 or otherfastening devices. As shown in FIGS. 1 and 4, the ends of the crossbars28 are cut to fit the irregular transverse cross sectional shape of thevertical frame members 24 thus providing tongue-like projections 78which extend into the trough-like contour that is afforded by the outertrough sides 34, the side rail portions 30, and the inturned flanges 42.

As best shown in FIGS. 4, 5 and 8, each crossbar 28 has associatedtherewith a reaction pin 80 which projects across the medial region ofthe crossbar, extends through aligned holes in the channel sides 70, andis disposed a slight distance inwards of the channel bottom 72; and thispin 80 is traversed by an elongated steel pre-tensioning rod 82 which isof wide angle V-shape and has inwardly diverging legs 83 the ends ofwhich are threaded as indicated at 84. The threaded ends 84 of the rods82 project through holes 86 (see FIG. 5) in the bottoms 38 of theintermediate trough section 33 of the vertical frame members 24. Saidthreaded ends 84 receive thereover washers 87 and nuts 88 by means ofwhich the rods 82, after tightening of the nuts in the direction of theadjacent trough bottoms 38, are placed under tension so that the apexregions of the rods are drawn hard against the rivets 80 and the rodsare thus placed under an appreciable degree of tension. Reference toFIG. 12 will reveal the fact that the various rods 82 are preformed intheir wide angle V-shape to facilitate their initial insertion into theinterior of the crossbars 28 and also alignment of the threaded rod ends84 with the holes 86 in the trough bottoms 38 of the trough sections 33of the vertical frame members 24. It is to be noted that the angularityof the diverging legs 83 of the rods 82 is commensurate with orcorresponds to the slope of the bottoms 38 of the intermediate troughsections 33 of the vertical frame members 24 so that, unlike the shankportions 56 of the bolts 52, it is not necessary to turn or bend thethreaded ends of the rods laterally out of alignment with the legs 83.

The manner in which adjacent panels 12 in the concrete wall form areassembled upon one another in their edge-to-edge relationship is bestillustrated in FIGS. 1, 2, 7 and 10 of the drawings. The assembly ismade by means of conventional T-bolts 90 which cooperate with specialwedge members 92, the latter being captured by the various crossbars 28and held against removal from the associated panel 12. An assembly ofsuch a T-bolt and such a wedge member in its free state is illustratedin FIG. 10 of the drawings. As clearly shown in FIGS. 1, 2 and 3, thevertical frame members 24 are provided with dados 94 in the vicinity ofthe crossbars 28, these dados being formed only in the inner side railportions 32 (see FIGS. 1, 2 and 9) which serve as protective flanges forthe edges of the plywood facing 20 of the concrete wall form panel 12.When a pair of adjacent panels are brought to their normal edge-to-edgerelationship, the dados 94 in the vertical flame members 24 of the twopanels register with each other (see FIG. 2) and provide voids forreceving the adjacent end portions of the flat slotted tie rods 18. Nodados are formed in the outer side rail portions 30 of the verticalframe members 24 and the adjacent tie rod end portions pass betweenthese opposed outer side rail portions of the vertical frame members ofthe adjacent panels. Thus, as shown in FIG. 1, the tie rod end portionsbetween adjacent panels 12 will fit within pairs of registering dados 94near the inner sides of the panels in the vicinity of the plywoodfacings 20 but will only bear against the outer side rail portions 30near the outer sides of the panels and establish gaps such a are shownat 100 in FIG. 1, such gaps being between the opposed side rail portions30 of the vertical frame members 24. Said outer rail portions 30 of thevertical frame members 24 are provided with rectangular slots 102 (seeFIGS. 2 and 9) in the vicinity of the crossbars 28, and these slots aredesigned for reception of the T-bolts 90. Each T-bolt 90 is of flatconstruction and has an enlarged T-head 104 (see FIG. 10) and anelongated further shown in FIG. 2 and the slot 108 in the shank movesinto vertical register with a pair of vertically aligned, longitudinallyextending slots 110 in the sides 70 of the adjacent channel-shapedcrossbar 28 near the adjacent end thereof. The associated wedge member92 of each T-bolt and wedge member assembly is generally of C-shapedesign and embodies upper and lower horizontal foot portions 112 and 114and a vertical connecting bight portion 116. The latter has an inclinedouter edge 118 which, in combination with the foot portions 112 and 114of the wedge assembly 92 effects the wedging action whereby a pair ofadjacent concrete wall form panels 12 are drawn hard against each otherin their edge-to-edge relationship. The bight portion 116 of the wedgemember 92 projects through the associated two aligned slots 110 in thechannel sides 70 of the adjacent crossbars 28 and also through the slot108 in the shank 106 of the associated T-bolt 90 with the inclined edge118 of said bight portion opposing the outer end of the T-bolt shank andwith the foot portions 112 and 114 of the wedge member 92 opposing andbearing against the inner surface of the outer side rail portion 30 ofthe adjacent vertical frame member 24. Thus, when the wedge member isdriven downwardly by striking the upper foot portion 112 thereof with animpact tool such as a sledge or a hammer, the wedge member will bedriven to the wedging position wherein it is shown in FIG. 2 (also fulllines in FIG. 7) and the associated T-bolt 90- will be placed undertension so as to draw the two opposed vertical frame members 24 of thetwo panels hard against each other.

The captured wedge member 92 is shown in its free state in FIG. 7 and itwill be observed that when such wedge is manually lifted to theuppermost position of which it is capable of assuming as shown in dottedlines, the lower or bottom edge thereof lies slightly above the level ofthe bolt-receiving slot 102 in the outer side rail portion 30 so thatthe associated T-bolt may be projected through the slot and the shank ofthe T-bolt caused to underlie the wedge member 92. With the T-bolt fullyprojected through the slot 102, as well as through a corresponding slot102 in the outer side rail portion of the adjacent vertical frame member24 of the adjacent panel 12, the lower foot portion 114 of the wedgemember 92 will be in vertical register with the elongated slot 108 inthe shank 106 of the T-bolt 90. Thereafter, the wedge member 92 may beforced downwardly so that the bight portion passes through said slot108. Thereafter a blow imparted to the upper foot portion 112 of thewedge member by an impact tool will tighten the wedge as heretoforedescribed. It should be observed at this point that captured wedges 92are not necessarily employed in connection with each of the variouscrossbars 28 since two or three fastening devices are consideredadequate to secure two panels 12 together in their edge-to-edgerelationship. The number of wedges that are associated with any givenconcrete wall form panel will be a function of the length of such panel.Thus in FIG. 1 no wedge is shown as being associated with the upper-mostcrossbars 28 of the panels 12. Ordinarily, the crossbars are disposed onone foot centers so that the use of Wedge members 92 with alternatelydisposed crossbars will suffice for a firm connection between adjacentpanels. It will be understood that wherever a wedge member 92 isemployed, such wedge will serve not only as a clamping means betweenadjacent panels but also as an anchor device for the adjacent endportion of an associated tie rod 96. The various tie rods are slotted asshown at 120 for reception of the shanks of the associated T-bolts 90with the tie rod end portion projecting through the voids which areestablished by the pairs of dados 94 as is customary in connection withthe fastening together of certain forms or types of steel-studdedconcrete wall form panels.

From the above description it will be apparent that concrete wall for-mpanels embodying the present invention are capable of being readilyassembled at the factory or dismantled and reassembled in the field forreplacement of parts if necessary. The nuts 88 which are associated withand normally mounted on the pretensioning rods 82 and the nuts 60 whichare associated with the fastening bolts 52 of the corner clampingassemblies are the only devices which hold the panel in its assembledrelationship. With these nuts removed, the vertical frame members 24 arereadily removable from the horizontal frame members 26, as well as fromthe ends of the crossbars 28. With the vertical frame members 24removed, the horizontal frame members 26 are freed for removal. So alsoare the pretensioning rods 82 which may be slid endwise from thecrossbars 28 which normally enclose them. Furthermore, as soon as thevertical frame members 24 of the rectangular reinforcing studding areremoved from the panel 12, the foot portions 112 and 114 of the variousWedge members 92 are no longer obstructed and at least one foot portionof each wedge is so dimensioned that it will slip through the twoaligned slots 110 in the sides 70 of the crossbar with which it isassociated.

It should be observed that in assembling a given concrete wall formpanel 12, as soon as the nuts 88 on the ends of the pretensioning rods80 are tightened, not only are the two vertical frame members 24 drawninwardly against the adjacent side edges of the plywood facing 20, butthe tension in the angular pretensioning rods is such that the reactionrivets 80 (see FIGS. 4 and 5) are urged in an inward or forwarddirection, thus tending to flex the crossbars inwardly against thedirection of outward thrust of the wet concrete when the latter ispoured against the plywood facing 20 of the panel. This pretensioning ofthe crossbars 28 is instrumental in resisting such outward thrust of theconcrete and preserving a truly straight linear configuration across theform panel at each crossbar level.

The invention is not to be limited to the exact arrangement of partsshown in the accompanying drawings or described in this specification asvarious changes in the details of construction may be resorted towithout departing from the spirit or scope of the invention. Forexample, whereas the various pretensioning rods 82 are shown as beingprovided with threaded portions 84 at the opposite ends thereof, it iscontemplated that these rods may be in the form of elongated bolts whichare bent to their proper wide angle V-shape configuration and haveenlarged heads so that the use of two nuts in connection with thetensioning thereof is eliminated, at single nut for each rod beingadequate for tensioning purposes. The use of the wood screws 76 forsecuring the plywood facings 20 to the outturned flanges 74 of thecrossbars 28 is purely optional and in instances where the plywoodfacing 20 is so dimensioned that it fits snugly between the two verticalframe members 24 and between the two horizontal frame members 26 beforethe nuts 60 and 88 are fully tightened, such wood screws may be omittedsince the subsequent pressure incident to further tightening of theaforesaid nuts will compress the plywood facing to such a degree that itwill be captured between the four frame members of the steel reinforcingstudding. In any event, the number of wood screws that need be employedwill be few since no appreciable degree of pressure on the panel facingtending to dislodge it is ordinarily encountered. It is furthercontemplated that, if desired, rivets may be substituted for the woodscrews but in such an instance that stated advantage of preserving asmooth unbroken panel facing contour throughout the entire life of thepanel is dispensed with. Other minor changes in the details ofconstruction of the concrete wall form panel 12 are contemplated.

Having thus described the invention what I claim as new and desire tosecure by Letters Patent is:

1. A concrete wall form panel comprising a rectangular facing surroundedby studding in the form of a rectangular metal frame including a pair ofoppositely disposed longitudinal frame members and a pair of oppositelydisposed transverse frame members, the front wall-forming side of saidfacing and the front rim of the frame lying in a common plane, and aseries of spaced parallel metal crossabrs which are of channel shape intransverse cross section extending between the longitudinal framemembers at a right angle thereto and arranged so that their channeledges bear against the rear side of the facing in reinforcing relationwith respect thereto, thus dividing the rectangular frame opening into aseries of included rectangular frame openings, a reaction pin projectingacross the channel sides of each crossbar at a region outwardlydisplaced fro-m the plane of the rectangular facing, and an elongatedtensioning rod projecting through each crossbar and having its endsattached to the longitudinal frame members at regions which are in closeproximity to the plane of the facing and its medial region passingacross and bearing against said reaction pin on the side thereof remotefrom the facing, said tensioning rod serving to bias the crossbar inflexion so as to urge said medial region toward the facing.

2. A concrete wall form panel as set forth in claim 1 and wherein theopposite ends of the tensioning rods are threaded, the longitudinalframe members are provided with holes through which said opposite endsof the tensioning rods project, and nuts are threadedly received on saidthreaded ends and, when tightened, serve to place the rods undertension.

3. A concrete wall form panel as set forth in claim 2 and wherein thelongitudinal frame members are formed with inwardly offset wall portionsestablishing trough-like recesses which are coextensive with said framemembers, the holes are formed in such inwardly offset wall portions,and'the nuts and threaded ends of the tensioning rods lie wholly withinthe confines .of said recesses.

4. A concrete wall form panel as set forth in claim 2 and including,additionally, releasable means at each corner of the rectangular metalframe for securing the adjacent ends of the longitudinal and transverseframe members together, said releasable means, in combination with saidtensioning rods and their associated nuts constituting means formaintaining the various components of the panel in its assembledrelationship.

5. A concrete wall form panel as set forth in claim 3 and wherein saidinwardly offset wall portions have bottoms which are inclined at a smallangle to a plane at right angles to the facing, and said threaded endsof the tensioning rods extend at right angles to said inclined bottomsof the offset wall portions and project therethrough.

6. A concrete wall form panel as set forth in claim 4 and wherein eachreleasable means comprises a bolt having a head portion seated withinthe trough-like recess of the associated transverse frame member andsecured to the inwardly offset Wall portion of said associatedtransverse frame member, a shank projecting through an opening in theinwardly offset wall portion of the associated longitudinal framemember, and a nut threadedly received on said shank and adapted to betightened against the last mentioned inwardly offset wall portion.

References Cited UNITED STATES PATENTS 2,258,694 10/1941 Wedberg 249-28X 2,818,629 1/1958 Wedberg 249-489 X I. SPENCER OVERHOLSER, PrimaryExaminer R. D. BALDWIN, Assistant Examiner US. 01. X.R. 249- 45

